Caribou are the staff of life in the northern Yukon.

They're also the standard by which the people of the north, for generations, have judged the state of the environment. If the caribou are plentiful and in good condition, then the world must be in good shape.

Now scientists, in cooperation with community hunters, are finding ways to do what northern peoples have always done -- use the Porcupine Caribou Herd to assess the state of the northern environment.

The Northern Yukon Ecological Knowledge Co-operative, part of the federal government's Ecological Monitoring and Assessment Network (EMAN), has identified the Porcupine Caribou Herd as one of the key indicators of environmental change in the north. Both scientists and people from northern communities will be keeping a close eye on the condition of the herd in the future.

The Yukon Department of Renewable Resources has already been collecting data on caribou body condition for several years. The goal of the data collection is to track long-term trends in body condition, says Dorothy Cooley, regional biologist in Dawson.

"Right now we're collecting baseline data," she says. "This data will be needed to make sense of other research on the reasons for fluctuations in condition."

The caribou body condition survey started a decade ago with a graduate student's research project at the University of Alaska Fairbanks. From 1987 to 1990, the researcher, Anne Allaye-Chan, collected carcasses of adult female caribou, took detailed measurements related to total body weight, total body protein, and total body fat, and linked specific measurements to over-all body condition.

In 1990 and 1991, Yukon government biologists collected samples to verify Allaye-Chan's findings. Since then, regular sampling has continued, with some changes.

In the original study, Allaye-Chan collected caribou cows four times a year, based on when the caribou were accessible. In June or July, they are on their calving grounds in Alaska, in September they are usually near Old Crow, and in November and March they can be found along the Dempster Highway.

Now that the study is entirely Canadian, the Alaska sampling in early summer has been dropped and samples are taken only three times a year, Cooley says.

She's also looking at ways to make the sampling procedure less expensive and more informative. Allaye-Chan's research proposed a number of ways to measure body condition, so Cooley is hoping to be able to track body condition through a limited sampling system that would allow more caribou to be examined.

She has been going out with hunters during the sampling periods, trying to take tissue samples and body fat measurements from about 60 animals a year. But that number is small in relationship to the size of the herd, and doing all the sampling herself gets expensive.

"About 2000 animals are killed each year by hunters," Cooley says. "That sample size just makes me drool."

Information from even a fraction of the animals killed by hunters would be a major improvement over the number she can sample on her own, so Cooley is recruiting hunters to help with the body condition survey.

"The hunters have a really good idea in their own minds of how fat a caribou is, so for the past two years I've been having hunters rate fat on a scale of one to five."

Hunters involved in the study also measure back fat on the carcasses and turn in a kidney for analysis. Cooley says she might also ask them to turn in other tissue samples.

"It's a balancing act because you can't ask the hunters to do too much," she says. "That's a fairly big commitment to make. They have to really believe in the project."

Many hunters are prepared to make the commitment, she says, as in communities like Old Crow, which still relies heavily on the herd for subsistence, people are deeply concerned about the condition of the caribou and the condition of the northern environment.

For more information about the caribou body condition survey, contact the Yukon Department of Renewable Resources. For information about EMAN and the Northern Yukon Ecological Knowledge Co-operative, contact the Canadian Wildlife Service, Environment Canada, Whitehorse.